Pathetic Vehicle Finance

Just over 2 years ago when I purchased my current vehicle they insisted that my payments need to go through on the 25th of each month. I repeatedly told them that I do not get paid on the 25th and their reply was that it is not a problem as their system waits for the money to enter the account and then take their amount. Please note I do not use overdraft, so this month as usual Wesbank tries to take there amount, unsuccessful. Get a transaction rejection and a penalty from FNB. I have tried contacting them and there system is down! And for the record I have received my salary on the 28th.